Luminous discharge device



Feb. 6, 1934. M MORRlsON LUMINOUS DISCHARGE DEVICE Filed March 5. 1929 INI/ENTOR,

Patented sa. s, 1934 UNITED STATES PATENT OFFICE LUMINOUS DISCHARGE DEVICE Application March 5, 1929. Serial No. 344,416

7 Claims.

The present invention relates to luminous discharge tubes of the gaseous ionization type such as are used for illuminating advertising signs and the like.

Among the objects of my invention are; to provide electrodes which will operate at a lower temperature per ampere per unit area of discharge surface than those of the prior art, to provide electrodes which are much less subject to sputtering, and to provide electrodes which have a. lower` vaporization rate than those of the prior art.

Further and other objects will be pointed out and obvious upon reading the specification, but

the novel features of my invention are more particularly set forth in the claims.

Referring to the drawing, Fig. 1 represents one embodiment of my invention partly in elevation and partly in section, together with a diagrammatic view of one of the circuits which I use in the employment of my invention; Fig. 2 is a plan View of the part 3 of Fig. 1, as viewed from the direction of the tubing 1; Fig. 3 is a plan view of the part 4 in Fig. 1, as viewed from the same direction as above but with part 3 removed.

In the prior art it has been customary in making luminous discharge devices to construct them such that the electrodes Yemployed necessarily receive all of the terminal ionization bombardment independent of whether all this electrode bombardment was essential to the operation of the tube.

In the operation of a luminous discharge device of the character hereinafter described, when excited by alternating current, it will be appreciated by those skilled in the art that at any instant of time one end of the tube is operating cathode while the other end is operating anode, and for some later instant of time the condition is reversed; that is, the electrode previously operating as anode now acts as cathode. and the end which previously operated as cathode now operates as anode.

I have discovered that under certain conditions with certain gas pressures, that it is not necessary that all of the cathode ray stream originating from the end operating as cathode fall upon the electrode operating as anode. Further, this unnecessary anode bombardment serves only to 1raise its temperature, thereby increasing its sputering.

I have discovered that interposing between the electrodes in the path oi the discharge stream one or more barriers, I can intercept considerable of the discharge bombardment in the tube and thereby relieve the electrodes of this duty oi taking care oi this excess energy.

I am aware that in the prior art in the manufacture of X-ray tubes, that targets have been employed interposed between the cathode and the anode for the production of X-rays on the face of the target. This is, however, not pertinent to the present invention, as will be pointed out and obvious upon the reading of the speclfications and,claims.

Referring to Fig. 1, 1 is a translucent tube having bulbous ends 2 and 5. The bulbous end 2 is formed by making an elongated hollow cylindrical portion with two annular recesses 6 and 7. 4 is 70 an electrode proper, and in the employment under description, is formed of a simple cross as illustrated in plan View in Fig. 3, the cross having notches near the end 8, Fig. l, so as to be firmly supported by the walls of the chamber 2 75 at the annular recessed portion 7, Fig. 1. Into the end of chamber 2, is a sealed-in lead-in conductor 10 extending to electrode 4 and welded thereto at the point 11. Conductor 10 is further provided with a welded-on cap 12 to protect the 80 lead-in conductor 1'0 at the point of emergence from the glass seal, as fully disclosed in my application, Serial No. 256,916, viiled February 25, 1928. In chamber 5, is illustrated a different type of anode 13, which is of a spherical form and having its spherical surface enclosed at point of emergence of the lead-in conductor 14, which is located at 15.

It will be appreciated that a substantially totally closed electrode such as 13 does not dis- 90 charge from its interior wall, as proven in one of the classical experiments by Clerk Maxwell. Therefore, the discharge surface of electrode 13 is its exterior area only.

In some cases I provide a chamber, such as 2, containing an electrode such as 4, which is supported bythe wall of the said chamber, with an exterior shell 16 tting the exterior surface of the chamber 2 and connected electrically to the leadin conductor 10, thus relieving the wall oi the chamber 2 of electrical stress in the neighborhood of points of contact o! the electrode 4 with the wall of the said chamber 2, such as at 8. Chambers 2 and 5 are further provided with barriers 3 and 17, which are shown in plan view in Fig. 2. The barrier 3 such as at 6 in the present embodiment has crimped portions 18, which lit into annular recesses such as at 6, thus holding the barrier 3 iirmly in place in the chamber 2, and likewise barrier 17 is similarly held in chamber 5.

Barriers 3 and 17 are not electrodes because they are not electrically connected to the electric circuit, and serve only as barriers in the path of the discharge stream between the electrodes 11 and 13.

18 is an alternating current generator which through leads 19 and 20 and through switch 21 supply primary 22 oi transformer 23 with alternating current energy. 24 is the secondary of transformer 23, which by means of leads 25 and 28 will supply high voltage alternating current to electrodes 4 and 13.

Tube 1 and chambers 2 and 5 are formed into a hermetically sealed envelope which contains rarefied sas.

'Ihis hermetically sealed envelope, together with its electrodes and barriers, are treated, pumped, washed and supplied with rareiied gas, and then sealed, as is well understood in the art.

In the operation oi' my device, the discharge stream emitted from the ends of tube 1 at points 27 and 28 is directed upon barriers 3 and 17, and considerable of the energy in the discharge stream is absorbed by these barriers, only a partial amount oi' it being absorbed by the electrodes 4 and 13.

By this construction, I have found that there is less vaporization of the electrodes 4 and 13, as well as less sputtering of these electrodes, than in the case of the operation of the device in the absence of the barriers 3 and 17.

It will be appreciated that in vthe operation of this device the discharge falling upon barrier 3, and of course, similarly upon barrier 17, produces a certain amount of energy absorption in these electrodes, which is turned into heat and partially dissipated through the walls of the envelope chamber 2 at points of contact in the neighborhood of 18 and the like. In this manner it would be appreciated that some of the discharge energy for the tube 1 is arrested by these barriers and dissipated through the walls of the envelope without that energy having to go through the electrodes. In some cases I prefer to bring the barrier metallically through the wall of the envelope into the surrounding air, to increase the cooling of the barrier as shown at 30 in Fig. 1.

It appears that the electrodes do not require all the available energy at the ends of the discharge stream to be dissipated on their surface and in their immediate neighborhood for the proper operation of the device, and, therefore, the interposition of the barriers relieves these electrodes of having to absorb an unnecessary amount of energy, and permit them to work at a higher current value per unit area of surface of the electrode, than is possible with similar discharge tubes of the prior art.

I 11nd that in the employment of my invention the effect of reducing the energy absorption per unit ot surface area on the electrodes, permits me to operate my electrodes successfully at a current density in excess oi' 1.5 square decimeters per ampere. without excessive sputtering and without detrimental vaporlzation to the electrodes.

I do not limit my invention to the exact structure illustrated in the one embodiment shown, as many diierent combinations oi' electrodes and barriers may be evolved in the employment of my invention.

Having described one embodiment oi' my invention, I claim:

1. In a luminous discharge device comprising an hermetically sealed envelope having an elongated restricted portion with enlarged ends and containing a rarefled gas within said envelope, an electrode disposed within each oi. the enlarged ends of said envelope and operable when supplied with electrical energy to cause a discharge through the elongated restricted portion of said envelope between said electrodes, and a baille plate of electrically conductive material disposed adjacent each of said electrodes in the path of discharge therebetween.

2. In a luminous discharge device compris ing an hermetically sealed envelope having an elongated restricted portion with enlarged ends and containing a rareiled gas within said envelope, an electrode disposed within each of the enlarged ends of said envelope and operable when supplied with electrical energy to cause a discharge through the elongated restricted portion of said envelope between said electrodes. and a bafiie plate of electrically conductive material disposed adjacent each oi' said electrodes in the path of discharge therebetween and insulated from said electrodes.

3. In a luminous discharge device comprising an hermetically sealed envelope having an elongated restricted portion with enlarged ends and containing a rareed gas within said envelope, an electrode disposed Within each o1' the enlarged ends of said envelope and operable when supplied with electrical energy to cause a discharge through the elongated restricted portion oi' said envelope between said electrodes, and a baille plate of electrically conductive material interposed between said electrodes and disposed sdjacent each of the latter in the path of discharge therebetween, said baille plates being insulated from said electrodes.

4. In a luminous discharge device comprising an hermetically sealed envelope having an elongated restricted portion with enlarged ends and containing a rareed gas within said envelope, an electrode disposed within each oi.' the enlarged ends of said envelope and operable when supplied with electrical energy to cause a discharge through the elongated restricted portion of said envelope' between said electrodes, and a baille plate of electrically conductive material interposed between said electrodes and disposed adjacent each of the latter in the normal path of discharge therebetween to deflect said discharge from its normal path during operation of said device, said baille plates being insulated from said electrodes.

5. In a luminous discharge device comprising an hermetically sealed envelope having an elongated restricted portion with enlarged ends and containing arareed gas within said envelope. an electrode disposed within each of the en larged ends of said envelope and operablewhen supplied with electrical energy to cause a discharge through the elongated restricted portion of said envelope between said electrodes, and means disposed adjacent each of said electrodes and directly in the path of discharge during op iii eration oi said device comprising a baille plate of electrically conductive material independent of said electrodes for absorbing a portion of the energy of the discharge stream by electrical bombardment thereof during operation of said ievice.

6. In a luminous discharge device comprising a restricted translucent tube with enlarged ends formed into a hermeticaily sealed envelope, containing rarefied gas and having electrodes therein, means interposed between said electrodes for ab sorbing a portion of the energy of the discharge stream of the said device under operation and means associated with the wall of one of the said ends for dissipating part of this absorbed energy into the air surrounding the walls of the glass envelope independently of the said electrodes.

"l, in a luminous discharge device comprising an hermetically sealed envelope having an elongated restricted portion with enlarged ends and containing a rareiled gas within said envelope, an electrode disposed within each end o! said envelope and operable when supplied with electrical energy to cause a discharge between said electrodes, a bafiie plate of electrically conductive material interposed between said electrodes adjacent each of the latter in the path of discharge therebetween for defiecting said discharge and means disposed exteriorly of said envelope adjacent one of said electrodes for reducing the electrical stress upon the walls of said envelope in the vicinity of said electrode.

MONTFORD MORRISON.

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